The increase of C-reactive protein (CRP) in serum though synthesized elsewhere has continuously been a puzzle. Recent studies from our laboratory have shown CRP to be related antigenically to catalases found in peroxisome of the liver cell. Additionally, CRP and CxRP have been shown to depress the oxidative function of D-amino acid and L-alpha OH acid oxidases. Furthermore, CRP has been shown to bind lymphocytes, possibly via the choline phosphate residues on phospholipid membranes. In this manner CRP appears to affect H3-thymidine incorporation into DNA of lymphocytes. At the present the relationship of CRP to peroxisomal enzymes and their relationship to overall immunological processes are presently being investigated.